Hi,
You have to be real careful when scalloping a Jem. The vine inlay is done first then scalloped and apparently Ibanez actually ruins many guitar necks before getting a good one because of the scalloping process. In my opinion scalloping does not need to be very deep at all, and can only hinder the tuning stability of the neck.
I have a jem and a
malmsteen strat, and even the Yng strat does not have a 4mm scallop!! More like a 1.85 mm depth. It only needs to give a clearance for your finger tip anyway.
Let me know how you go on,
Col